Polyester resin composition

ABSTRACT

This invention is a polyester resin composition comprising 100 parts by weight of a resin composition consisting of 60 to 95 wt % of (a) a polyester resin and 5 to 40 wt % of (b) an olefin-based resin, and 0.5 to 30 parts by weight of (c) one or more resins selected from polyphenylene sulfide resins and liquid crystal resins, wherein said olefin-based resin (b) is composed of (b-1) a functional group-containing olefin copolymer having at least one kind of functional groups selected from carboxylic acid groups, carboxylic anhydride groups, carboxylic ester groups, metal carboxylate groups and epoxy groups and (b-2) an ethylene/α-olefin copolymer obtained by copolymerizing ethylene and an a-olefin with 3 to 20 carbon atoms; and the polyester resin (a) forms a continuous phase, while the olefin-based resin (b) is dispersed as particles with an average particle size of 0.01 to 2 μm in the composition. This invention provides a polyester resin composition having excellent flexibility and impact resistance in a low-temperature atmosphere, also having excellent flowability and chemicals resistance, and suitable for injection molding.

TECHNICAL FIELD

This disclosure relates to a polyester resin composition havingexcellent mechanical properties, especially excellent flexibility andimpact properties in a low temperature atmosphere as low as −40° C. andalso having excellent chemicals resistance and flowability.

BACKGROUND

Polyester resins typified by polyethylene terephthalate and polybutyleneterephthalate are used as various electric and electronic parts,mechanical parts, automobile parts, etc., since they have excellentproperties.

However, since polyester resins are inferior in impact properties,especially notched impact strength, many proposals have been proposedfor improving them. Among them, methods of blending a copolymer obtainedfrom such monomers as an α-olefin and an α,β-unsaturated acid glycidylester are popularly used. The molded parts obtained by these methodsshow good impact properties at near room temperature but have a problemthat they considerably decline in impact properties, for example, in alow temperature atmosphere of about −40° C. So, means for improving theimpact properties at low temperature are disclosed, and they include amethod of adding a specific glycidyl group-containing olefin copolymerand an ethylene/α-olefin copolymer (U.S. Pat. No. 4,461,871,US2002/91196), a method of adding an ethylene-vinyl acetate-basedcopolymer (U.S. Pat. No. 5,219,941), a method of adding an impactproperties ingredient having an acid anhydride group and a specificglycidyl group-containing olefin copolymer (U.S. Pat. No. 6,660,796),etc. A means in which an impact properties improving material is addedto a polyester resin and polyphenylene sulfide resin for enhancingimpact properties is also disclosed (JP6-23300B).

However, even if these proposed conventional methods are used, anycomposition having an impact strength of 500 J/m or more in a lowtemperature atmosphere cannot be obtained. So, it is demanded to developa material satisfying higher low-temperature properties. Furthermore,since the compositions obtained by these prior art are not satisfactoryin the chemicals resistance against acids, alkalis and organic solvents,they are limited in applicability. Improvement in this regard is alsodesired.

It could therefore be advantageous to obtain a polyester resincomposition having more excellent flexibility and impact properties in alow-temperature atmosphere than the conventional materials and alsohaving excellent flowability and chemicals resistance.

SUMMARY

We found that a resin composition consisting of a polyester resin, aspecific olefin-based resin, and a polyphenylene sulfide resin or aliquid crystal resin, in which a specific morphology is formed.

That is, We provide a polyester resin composition comprising 100 partsby weight of a resin composition consisting of 60 to 95 wt % of (a) apolyester resin and 5 to 40 wt % of (b) an olefin-based resin, and 0.5to 30 parts by weight of (c) one or more resins selected frompolyphenylene sulfide resins and liquid crystal resins, wherein saidolefin-based resin (b) is composed of(b-1) a functional group-containingolefin copolymer having at least one kind of functional groups selectedfrom carboxylic acid groups, carboxylic anhydride groups, carboxylicester groups, metal carboxylate groups and epoxy groups and (b-2) anethylene/α-olefin copolymer obtained by copolymerizing ethylene and anα-olefin with 3 to 20 carbon atoms; and the polyester resin (a) forms acontinuous phase, while the olefin-based resin (b) is dispersed asparticles with an average particle size of 0.01 to 2 μm in thecomposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a model drawing showing a sea-island structure in which apolyester resin forms a continuous phase while an olefin-based resin isdispersed.

FIG. 2 is a model drawing showing a co-continuous phase structure inwhich a poly-ester resin and an olefin-based resin form continuousphases together.

Meaning of symbols:

-   -   1. Polyester resin    -   2. Olefin-based resin

DETAILED DESCRIPTION

The polyester resin (a) is a polymer having ester bonds in its mainchain. It can be suitably a thermoplastic polyester having aromaticrings in the chain units of the polymer. Particularly it can be apolymer or copolymer obtained by a condensation reaction usually with anaromatic dicarboxylic acid (or any of its ester forming derivatives) anda diol (or any of its ester forming derivatives) and/or ahydroxycarboxylic acid as main ingredients.

Examples of the aromatic dicarboxylic acid include terephthalic acid,isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid,1,5-naphthalenedicarboxylic acid, bis(p-carboxyphenyl)methane,anthracenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid,1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalicacid and their ester forming derivatives. Two or more of these aromaticdicarboxylic acids can also be used together. Furthermore, aliphaticdicarboxylic acids such as adipic acid, sebacic acid, azelaic acid anddodecanedioic acid, alicyclic dicarboxylic acids such as1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid,and their ester forming derivatives can also be used together.

Examples of the diol include aliphatic diols with 2 to 20 carbon atomssuch as ethylene glycol, propylene glycol, 1,4-butanediol, neopentylglycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol,cyclohexanedimethanol, and cyclohexanediol, and their ester formingderivatives. Two or more of these diols can also be used together.

Examples of the polyester preferably usable in this invention includepolyalkylene terephthalates such as polyethylene terephthalate,polypropylene terephthalate, polybutylene terephthalate,polycyclohexanedimethylene terephthalate, and polyhexyleneterephthalate, polyethylene-2,6-naphthalene dicarboxylate,polybutylene-2,6-naphthalene dicarboxylate,polyethylene-1,2-bis(phenoxy)ethane-4,4′-dicarboxylate, and furthermorenon-liquid crystalline polyesters such as polyethyleneisophthalate/terephthalate, polybutylene isophthalate/terephthalate,polybutylene terephthalate/decanedicarboxylate, poly(ethyleneterephthalate/cyclohexanedimethylene terephthalate), andpolyethylene-4,4′-dicarboxylate/terephthalate, and their mixtures. Morepreferred are polyethylene terephthalate, polybutylene terephthalate,and polyethylene-2,6-naphthalene dicarboxylate. Especially preferred ispolyethylene terephthalate. Using these polyester resins as a mixture isalso practically suitable, depending on such required properties asmoldability, heat resistance, toughness and surface properties.

The method for producing the polyester resin (a) is not especiallylimited, and a publicly known conventional direct polymerization orester interchange method can be used for producing it.

The polymerization degree of the polyester resin is not limited, but itis preferred that, for example, the intrinsic viscosity measured in 0.5%o-chlorophenol solution at 25° C. is in a range from 0.35 to 2.00. Amore preferred range is from 0.50 to 1.50, and an especially preferredrange is from 0.50 to 1.20.

Furthermore, it is preferred that the amount of carboxyl end groups ofthe polyester resin (a) per ton of the polymer, obtained bypotentiometric titration of its m-cresol solution using an alkalisolution, is as relatively large as 30 to 80 eq/t in view of exhibitedlow-temperature impact properties. A more preferred range of the amountof the car-boxyl end groups is from 35 to 75 eq/t, and an especiallypreferred range is from 40 to 70 eq/t. It is not preferred that theamount of carboxyl end groups is smaller than 30 eq/t, sincelow-temperature properties tend to decline, and it is not preferredeither that the amount is larger than 80 eq/t, since hydrolysisresistance tends to decline.

Next, the olefin-based resin (b) consists of a functionalgroup-containing olefin copolymer (b-1) and an ethylene/α-olefincopolymer (b-2).

The functional group-containing olefin copolymer (b-1) is an olefincopolymer having at least one kind of functional groups selected fromcarboxylic acid groups, carboxylic anhydride groups, carboxylic estergroups, metal carboxylate groups and epoxy groups. In this case, theolefin copolymer having functional groups can be obtained byin-troducing a monomer as a component having at least one functionalgroup selected from a carboxylic acid group, carboxylic anhydride group,carboxylic ester groups, metal carboxylate group and epoxy group, intoan olefin copolymer. used for producing it.

The monomer as a component having a functional group used forintroducing functional groups into the olefin copolymer is a compoundcontaining a carboxylic acid group, carboxylic anhydride group,carboxylic ester groups, epoxy group, etc. Examples of the monomer as acomponent having a functional group include unsaturated dicarboxylicacids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid,tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid,isocrotonic acid, norbornenedicarboxylic acid, andbicycle[2,2,1]hepto-2-ene-5,6-dicarboxylic acid, and their carboxylicanhydrides, carboxylates, etc. Particular examples of the compoundinclude maleic anhydride, itaconic anhydride, citraconic anhydride,tetra-hydrophthalic anhydride,bicycle[2,2,1]hepto-2-ene-5,6-dicarboxylic anhydride, dimethyl maleate,monomethyl maleate, diethyl maleate, diethyl fumarate, dimethylitaconate, diethyl citraconate, dimethyl tetrahydrophthalate, dimethylbicycle[2,2,1]hepto-2-ene-5,6-dicarboxylate, hydroxyethyl acrylate,hydroxyethyl methacrylate, hydroxypropyl acrylate, propyl methacrylate,glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidylitaconate, glycidyl citraconate, aminoethyl methacrylate, aminopropylmethacrylate, etc.

The method for introducing the monomer as a component having afunctional group is not especially limited. Usable methods include amethod in which the monomer as a component having a functional group iscopolymerized together with at least one olefin selected from ethyleneand α-olefins, and a method in which the monomer is graft-introducedinto an olefin-based polymer.

As at least one olefin selected from ethylene and α-olefins used in thecopolymerization, it is preferred to use an olefin selected fromethylene and x-olefins with 3 to 20 carbon atoms. Examples of the olefininclude ethylene and other olefins such as propylene, 1-butene,2-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene,3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene,4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene,3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene,1-hexadecene, 1-octadecene, and 1-eicocene. Among them, one or moreolefins selected from ethylene, propylene, 1-butene, 4-methyl-1-pentene,1-hexene, and 1-octent are preferred.

Examples of the olefin-based polymer into which the monomer as acomponent having a functional group is graft-introduced include highdensity polyethylene, medium density polyethylene, low densitypolyethylene, polypropylene, ethylene/propylene copolymer,ethylene/butene-1 copolymer, ethylene/hexene-1 copolymer,ethylene/propylene/dicyclopentadiene copolymer,ethylene/propylene/5-ethylidene-2-norbornene copolymer, non-hydrogenatedor hydrogenated styrene/isoprene/styrene triblock copolymer,non-hydrogenated or hydrogenated styrene/butadiene/styrene triblockcopolymer, etc.

Moreover, in the case where the monomer as a component having afunctional group is graft-introduced into the olefin-based polymer, itis preferred that the graft introduction is performed in the presence ofa radical initiator, since the graft reaction efficiency can beenhanced. The radical initiator used here can be an organic peroxide orazo compound, etc. Examples of the radical initiator include dicumylperoxide, di-t-butyl peroxide,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane,2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3,1,3-bis(t-butylperoxyisopropyl)benzene,1,1-bis(t-butylperoxy)valerate, benzoyl peroxide, t-butylperoxybenzoate, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide,decanoyl peroxide, lauroyl peroxide, 3,5,5-tri-methylhexanoyl peroxide,2,4-dichlorobenzoyl peroxide, m-toluoyl peroxide, etc. Furthermore,examples of the azo compound include azoisobutyronitrile, dimethylazoisobutyronitrile, etc.

The reaction condition of the above-mentioned graft reaction is notespecially limited, but it is preferred that the reaction is performedwith the olefin-based polymer kept molten. That is, the graftpolymerization reaction is performed at a temperature higher than themelting point of said olefin copolymer, particularly usually in a rangefrom 80 to 300° C., preferably in a range from 80 to 260° C.

Furthermore, the olefin copolymer having metal carboxylate groups is anolefin co-polymer obtained by partially or wholly converting thecarboxylic acid introduced as described above into a metal salt. Themetal in the metal carboxylate groups is not especially limited.Examples of the metal include alkali metals and alkaline earth metalssuch as Li, Na, K, Mg, Ca, Sr and Ba, and also Al, Sn, Sb, Ti, Mn, Fe,Ni, Cu, Zn, Cd, etc. Especially Zn can be preferably used.

It is preferred that the amount of the monomer component containing afunctional group is from 0.001 to 40 mol % based on the total amount ofthe functional group-containing olefin copolymer (b-1). A more preferredrange is from 0.01 to 35 mol %.

As the functional group-containing olefin copolymer (b-1), an olefincopolymer containing epoxy groups is preferred. The olefin copolymercontaining epoxy groups means an olefin copolymer containing at leastone epoxy group in the molecule. Preferred is any of olefin copolymersobtained by using ethylene andlor an α-olefin and an α,β-unsaturatedcar-boxylic acid glycidyl ether as comonomers. These copolymers can alsobe further copolymerized with an α,β-unsaturated carboxylic acid or anyof its alkyl esters such as acrylic acid, methyl acrylate, ethylacrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethylmeth-acrylate or butyl methacrylate.

It is especially preferred to use an olefin copolymer obtained by usingethylene and an α,β-unsaturated carboxylic acid glycidyl ester ascomonomers. More particularly it is especially preferred to use anolefin copolymer obtained by using 60 to 99 wt % of ethylene and 1 to 40wt % of an α,β-unsaturated carboxylic acid glycidyl ester as comonomers.

Said α,β-unsaturated carboxylic acid glycidyl ester is a compoundrepresented by

(where R denotes a hydrogen atom or lower alkyl group). Examples of itinclude glycidyl acry-late, glycidyl methacrylate, glycidyl ethacrylate,etc. Among them, glycidyl methacrylate can be preferably used.

Examples of the olefin copolymer obtained by using ethylene and/or anα-olefin and an α,β-unsaturated carboxylic acid glycidyl ester asessential comonomers include ethylene/propylene/glycidyl methacrylatecopolymer, ethylene/butene-1/glycidyl methacrylate copolymer,ethylene/glycidyl acrylate copolymer, ethylene/glycidyl methacrylatecopolymer, ethylene/methyl acrylate/glycidyl methacrylate copolymer, andethylene/methyl methacrylate/glycidyl methacrylate copolymer. Amongthem, ethylene/glycidyl methacrylate copolymer, ethylene/methylacrylate/glycidyl methacrylate copolymer, and ethylene/methylmethacrylate/glycidyl methacrylate copolymer can be preferably used.

Furthermore, the ethylene/a-olefin copolymer (b-2) obtained fromethylene and an α-olefin with 3 to 20 carbon atoms is a copolymerconsisting of ethylene and one or more α-olefins with 3 to 20 carbonatoms as components. Examples of the α-olefin with 3 to 20 carbon atomsinclude propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene,1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene,1-eicocene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene,4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene,4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene,9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetra-decene, andtheir combinations. Among these α-olefins, a copolymer obtained by usingan α-olefin with 6 to 12 carbon atoms is preferred, since a higherimpact strength and a further higher reforming effect can be achieved.

It is preferred that the melt flow rate (hereinafter abbreviated as MFR:measured according to ASTM D 1238 at 190° C. at 2160 g load) of theolefin-based resin (b) is from 0.01 to 70 g/10 mm. A more preferredrange is from 0.03 to 60 g/10 mm. It must be noted that if MFR is lessthan 0.01 g/10 min flowability becomes low, and that if it is more than70 g/10 min, the impact strength may decline, depending on the form ofthe molded part.

The method for producing the olefin-based resin (b) is not especiallylimited. Any method selected from radical polymerization, coordinationpolymerization using a Ziegler Natta catalyst, anionic polymerization,coordination polymerization using a metallocene catalyst, etc. can beused.

The mixing ratio of the polyester resin (a) and the olefin-based resin(b) of this invention is 60 to 95 wt % of the polyester resin and 5 to40 wt % of the olefin-based resin. A preferred ratio is 70 to 85 wt % ofthe polyester resin and 15 to 30 wt % of the olefin-based resin. It isnot preferred that the amount of the olefin-based resin is smaller than5 wt %, since it is difficult to obtain the effect of improvingflexibility and impact properties. It is not preferred either that theamount is larger than 40 wt % on the contrary, for such reasons that thethermal stability and chemicals resistance peculiar to the polyesterresin are impaired and that the viscosity during melt kneading becomeslarge.

Moreover, it is preferred that the ratio of the functionalgroup-containing olefin copolymer (b-1) to the ethylene/α-olefincopolymer (b-2) is such that the amount of the ingredient (b-1) is from5 to 40 wt % while the amount of the ingredient (b-2) is from 60 to 95wt % based on the total amount of both. It is more preferred that theamount of the ingredient (b-1) is from 10 to 30 wt % while the amount ofthe ingredient (b-2) is from 70 to 90 wt %. If the amount of theingredient (b-1) is smaller than 5 wt %, it tends to be difficult toobtain low-temperature properties. If the amount is larger than 40 wt %,the viscosity during melt kneading tends to be so large as to lower theflowability. Furthermore, if the amount of the ingredient (b-2) issmaller than 60 wt %, it tends to be difficult to obtain low-temperatureproperties, and if the amount is larger than 95 wt %, the chemicalsresistance tends to decline.

To further improve chemicals resistance and imparting such properties asflowability during processing without impairing the toughness and impactproperties at low temperature, it is necessary to let the polyesterresin composition contain one or more resins (c) selected frompolyphenylene sulfide resins (hereinafter abbreviated as PPSs) andliquid crystal resins.

As the PPS (c), a polymer having recurring units represented by thefollowing structural formula can be used.

In view of heat resistance, a polymer containing 70 mol % or more,especially 90 mol % or more of the recurring units represented by saidstructural formula is preferred. Furthermore, the PPS can contain lessthan about 30 mol % of recurring units having any of the followingstructures, etc. Above all, for example, p-phenylene sulfide/m-phenylenesulfide copolymer (containing 20% or less of m-phenylene sulfide units)can be preferably used, since it has both moldability and barrierproperties.

Such a PPS can be produced at a high yield by recovering andpost-treating the PPS obtained by letting a polyhalogen aromaticcompound and a sulfidizing agent react with each other in a polarorganic solvent. Concretely it can also be produced by the method ofobtaining a polymer with a relatively low molecular weight described inJP45-3368B, or the method of obtaining a polymer with a relatively highmolecular weight described in JP52-12240B or JP61-7332A, etc. The PPSobtained as described above can also be variously treated, for example,by heating in air for crosslinking/increasing its molecular weight,heat-treating in an inert gas atmosphere such as nitrogen or underreduced pressure, washing with an organic solvent, hot water or acidaqueous solution, etc., activating using a functional group-containingcompound such as an acid anhydride, amine, isocyanate, functionalgroup-containing disulfide compound, before it is used.

The particular method for heating the PPS for crosslinking/increasingthe molecular weight can be a method in which the PPS is heated in anoxidizing gas atmosphere such as air or oxygen or in a mixed gasatmosphere consisting of said oxidizing gas and an inert gas such asnitrogen or argon at a predetermined temperature in a heating vesseltill a desired melt viscosity can be obtained. The heat treatmenttemperature is usually selected in a range from 170 to 280° C. Apreferred range is from 200 to 270° C. Furthermore, the heat treatmenttime is usually selected in a range from 0.5 to 100 hours. A preferredrange is from 2 to 50 hours. If both of them are controlled, theintended viscosity level can be obtained. The heat treatment apparatuscan be an ordinary hot air dryer, a rotary heater or a heater withstirring blades. In view of efficient and more uniform treatment, it ispreferred to use a rotary heater or a heater with stirring blades.

The particular method for heat-treating the PPS (c) in an inert gasatmosphere such as nitrogen or under reduced pressure can be a method inwhich the PPS is heat-treated in an insert gas atmosphere such asnitrogen or under reduced pressure at a heat treatment temperature of150 to 280° C., preferably 200 to 270° C. for a heating time of 0.5 to100 hours, preferably 2 to 50 hours. The heat treatment apparatus can bean ordinary hot air dryer, a rotary heater or a heater with stirringblades. However, in view of efficient and more uniform treatment, it ispreferred to use a rotary heater or a heater with stirring blades.

It is preferred that the PPS (c) is a PPS treated with washing. Examplesof the washing treatment method include acid aqueous solution washingtreatment, hot water washing treatment, organic solvent washingtreatment, etc. Two or more of these washing treatment methods can alsobe used in combination.

The particular method for washing the PPS with an organic solvent can beas exemplified below. The organic solvent used for washing the PPS isnot especially limited if it does act on the PPS, for example, if itdoes not decompose the PPS. Examples of the organic solvent includenitrogen-containing polar solvents such as N-methylpyrrolidone,dimethylformamide and dimethylacetamide, sulfoxide-based and sulfo-basedsolvents such as dimethyl sulfoxide and dimethyl sulfone, ketone-basedsolvents such as acetone, methyl ethyl ketone, diethyl ketone andacetophenone, ether-based solvents such as dimethyl ether, dipropylether and tetrahydrofuran, halogen-based solvents such as chloroform,methylene chloride, trichloroethylene, ethylene dichloride,dichloroethane, tetrachloroethane and chlorobenzene, alcohol-based andphenol-based solvents such as methanol, ethanol, propanol, butanol,pentanol, ethylene glycol, propylene glycol, phenol, cresol andpolyethylene glycol, aromatic hydrocarbon-based solvents such asbenzene, toluene and xylene. Among these organic solvents, it ispreferred to use N-methylpyrrolidone, acetone, dimethylformamide,chloroform, etc. Any one of these organic solvents can be used, or twoor more of them can also be used as a mixture. The method for washingthe PPS with an organic solvent can be, for example, a method in whichthe PPS is immersed in an organic solvent. As required, adequatestirring or heating can also be used. The washing temperature forwashing the PPS with an organic solvent is not especially limited, and adesired temperature can be selected in a range from room temperature toabout 300° C. If the washing temperature is higher, the washingefficiency tends to be higher, but usually a washing temperature in arange from room temperature to 150° C. assures a sufficient effect.Furthermore, it is preferred that the PPS washed with an organic solventis washed with cold or warm water several times for removing theremaining organic solvent.

As the particular method for washing the PPS with hot water, thefollowing method can be exemplified. To exhibit a preferred effect ofchemically modifying the PPS by hot water washing, it is preferred thatthe water used is distilled water or deionized water. The operation ofhot water treatment is usually performed by adding the PPS into apredetermined amount of water and heating and stirring at atmosphericpressure or in a pressure vessel. As for the ratio between PPS andwater, it is preferred that the amount of water is larger. Usually thebath ratio is selected to ensure that 200 g or less of the PPS is addedinto 1 liter of water.

Moreover, in the case where the PPS is washed with hot water, it ispreferred to use an aqueous solution containing a group II metal elementof the periodic table for treatment. The aqueous solution containing agroup II metal element of the periodic table is obtained by adding awater soluble salt of a group II metal element of the periodic table tosaid water. It is preferred that the concentration of the water solublesalt of a group II metal element of the periodic table based on theamount of water is in a range from about 0.001 to about 5 wt %.

Preferred examples of the metal element used among the group II metalelements of the periodic table include Ca, Mg, Ba, Zn, etc. Examples ofthe counter anions include acetate ions, halide ions, hydroxide ions,carbonate ions, etc. More particular and suitable examples of thecompound include calcium acetate, magnesium acetate, zinc acetate,CaCl₂, CaBr₂, ZnCl₂, CaCO₃, Ca(OH)₂, CaO, etc. Especially preferred iscalcium acetate.

It is preferred that the temperature of the aqueous solution containinga group II metal element of the periodic table is 130° C. or higher.More preferred is 150° C. or higher. The upper limit of the washingtemperature is not especially limited. However, in the case where anordinary autoclave is used, about 250° C. is the limit.

It is preferred that the bath ratio is selected to ensure that the ratioof (the weight of the dry polymer: the weight of the aqueous solutioncontaining a group II metal element of the periodic table) is kept in arange from 1:2 to 1:100. A more preferred range is from 1:4 to 1:50, anda further more preferred range is from 1:5 to 1:15.

The particular method for washing the PPS with an acid aqueous solutionis exemplified below. That is, for example, a method in which the PPS isimmersed in an acid or an acid aqueous solution can be used, and asrequired, adequate stirring or heating can also be used. The acid usedis not especially limited, if it does not act to decompose the PPS.Examples of the acid include aliphatic saturated monocarboxylic acidssuch as formic acid, acetic acid, propionic acid and butyric acid,halo-substituted aliphatic saturated carboxylic acids such aschloroacetic acid and dichloroacetic acid, aliphatic unsaturatedmonocarboxylic acids such as acrylic acid and crotonic acid, aromaticcarboxylic acids such as benzoic acid and salicylic acid, dicarboxylicacids such as oxalic acid, malonic acid, succinic acid, phthalic acidand fumaric acid, inorganic acidic compounds such as sulfuric acid,phosphoric acid, hydrochloric acid, carbonic acid and silicic acid.Among them, acetic acid and hydrochloric can be more preferably used. Itis preferred that the PPS treated with such an acid is washed with coldor warm water several times for removing the remaining acid, salt, etc.It is preferred that the water used for washing is distilled water ordeionized water, lest the preferred effect of chemically modifying thePPS by the acid treatment should be impaired.

It is preferred that the ash content of the PPS (c) is in a relativelylarge range from 0.1 to 2 wt % for imparting the flowability duringprocessing and properties such as fast molding cycles. A more preferredrange is from 0.2 to 1 wt %, and a further more preferred range is from0.3 to 0.8 wt %.

The ash content in this case refers to the amount of inorganiccomponents in the PPS obtained by the following method.

-   -   (1) Five to six grams of the PPS are weighed and placed on a        platinum dish burned at 583° C. and cooled.    -   (2) The PPS is preliminarily burned at 450 to 500° C. together        with the platinum dish.    -   (3) The preliminarily burned PPS sample is placed in a muffle        furnace set at 583° C. together with the platinum dish, and        burned for about 6 hours till it is perfectly incinerated.    -   (4) It is cooled in a desiccator and weighed.    -   (5) The ash content is calculated from the following formula:        Ash content (wt %)=(Weight of ash (g)/Weight of the sample        (g))×100

It is preferred that the melt viscosity of the PPS (c) is in a rangefrom 1 to 2000 Pa·s (300° C., shear rate 1000 sec⁻¹) in view of higherchemicals resistance and such properties as flowability duringprocessing. A more preferred range is from 1 to 200 Pa·s, and a furthermore preferred range is from 1 to 50 Pa·s. The melt viscosity in thiscase is a value measured using a Koka type flow tester and a nozzle witha nozzle diameter of 0.5 mm and a nozzle length of 10 mm at a shear rateof 1000 sec⁻¹.

It is preferred that the chloroform extraction content (calculated fromthe amount remaining after 5-hour Soxhlet extraction of 10 g of thepolymer using 200 mL of chloroform) as an indicator of the oligomercontent of the PPS (c) is in a relatively large range from 1 to 5 wt %for improving the chemicals resistance and imparting such properties asflowability during processing. A more preferred range is from 1.5 to 4wt %, and a further more preferred range is from 2 to 4 wt %.

The liquid crystal resin (c) is a resin capable of forming ananisotropic melt phase. It is preferred that the resin has ester bonds.The resin is, for example, a liquid crystal polyester composed ofstructural units selected from aromatic oxycarbonyl units, aromaticdioxy units, aromatic and/or aliphatic dicarbonyl units, alkylenedioxyunits, etc. and capable of forming an anisotropic melt phase, or aliquid crystal polyester amide composed of said structural units andstructural units selected from aromatic iminocarbonyl units, aromaticdiimino units, aromatic iminoxy units, etc. and capable of forming ananisotropic melt phase.

The aromatic oxycarbonyl units can be structural units produced, forexample, from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, etc.The aromatic dioxy units can be structural units produced, for example,from 4,4′-dihydroxybiphenyl, hydroquinone,3,3′,5,5′-tetra-methyl-4,4′-dihydroxybiphenyl, t-butylhydroquinone,phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,2,2-bis(4-hydroxyphenyl)propane, 4,4′-dihydroxydiphenyl ether, etc. Thearomatic and/or aliphatic dicarbonyl units can be structural unitsproduced, for example, from terephthalic acid, isophthalic acid,2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid,1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid,1,2-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, adipic acid, sebacic acid, etc. Thealkylenedioxy units can be structural units produced, for example, fromethylene glycol, 1,3-propylene glycol, 1,4-butanediol (among them,structural units produced from ethylene glycol are preferred), etc. Thearomatic iminoxy units can be structural units produced, for example,from 4-aminophenol, etc.

Examples of the liquid crystal polyester include a liquid crystalpolyester composed of structural units produced from p-hydroxybenzoicacid and 6-hydroxy-2-naphthoic acid, a liquid crystal polyester composedof structural units produced from p-hydroxybenzoic acid, structuralunits produced from 6-hydroxy-2-naphthoic acid, and structural unitsproduced from an aromatic dihydroxy compound and/or aliphaticdicarboxylic acid, a liquid crystal polyester composed of structuralunits produced from p-hydroxybenzoic acid, structural units producedfrom 4,4′-dihydroxybiphenyl, and structural units produced fromaliphatic dicarboxylic acids such as terephthalic acid and/or adipicacid, and sebacic acid, a liquid crystal polyester composed ofstructural units produced from p-hydroxybenzoic acid, structural unitsproduced from ethylene glycol, and structural units produced fromterephthalic acid, a liquid crystal polyester composed of structuralunits produced from p-hydroxybenzoic acid, structural units producedfrom ethylene glycol, and structural units produced from terephthalicacid and isophthalic acid, a liquid crystal polyester composed ofstructural units produced from p-hydroxybenzoic acid, structural unitsproduced from ethylene glycol, structural units produced from4,4′-dihydroxybiphenyl, and structural units produced from aliphaticdicarboxylic acids such as terephthalic acid and/or adipic acid, andsebacic acid, a liquid crystal polyester composed of structural unitsproduced from p-hydroxybenzoic acid, structural units produced fromethylene glycol, structural units produced from an aromatic dihydroxycompound, and structural units produced from aromatic dicarboxylic acidssuch as terephthalic acid, isophthalic acid and2,6-naphthalenedicarboxylic acid.

Above all, preferred examples of the liquid crystal polyester capable offorming an anisotropic melt phase include a liquid crystal polyestercomposed of structural units of (I), (II), (III) and (IV) represented bythe following general formulae, a liquid crystal polyester composed ofstructural units of (I), (III) and (IV), etc.

Especially preferred is a liquid crystal polyester composed ofstructural units of (I), (II), (III) and (IV).

(where R₁ denotes at least one or more groups selected from thefollowing general formulae:

R₂ denotes one or more groups selected from the following generalformulae:

and X denotes a hydrogen atom or chlorine atom.)

The structural units (I) are structural units produced fromp-hydroxybenzoic acid. The structural units (II) are structural unitsproduced from one or more aromatic dihydroxy compounds selected from4,4′-dihydroxybiphenyl, 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenyl,hydroquinone, t-butylhydroquinone, phenylhydroquinone,methylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,2,2-bis(4-hydroxyphenyl)propane and 4,4′-dihydroxydiphenyl ether. Thestructural units (III) are structural units produced from ethyleneglycol. The structural units (IV) are structural units produced from oneor more aromatic dicarboxylic acids selected from terephthalic acid,isophthalic acid, 4,4′-diphenyldicarboxylic acid,2,6-naphthalenedicarboxylic acid,1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid,1,2-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid and 4,4′-diphenylether dicarboxylic acid. Among them, structural units, in which R₁denote the following formula

and R₂ denotes the following formula

are especially preferred.

The preferred liquid crystal polyester is, as described above, one ormore selected from copolymers composed of structural units (I), (III)and (IV) and co-polymers composed of structural units (I), (II), (III)and (IV), and the amounts of said structural units (I), (II), (III) and(IV) copolymerized can be decided as desired. However, to exhibit theproperties of this invention, it is preferred that the amounts of therespective structural units to be copolymerized are as follows.

In the case where the copolymer is composed of the structural units (I),(II), (III) and (IV), it is preferred that the total amount of thestructural units (I) and (II) to be copolymerized is from 30 to 95 mol %based on the total amount of the structural units (I), (II) and (III) tobe copolymerized. An especially more preferred range is from 40 to 85mol %. Furthermore, it is preferred that the amount of the structuralunits (III) to be copolymerized is from 70 to 5 mol % based on the totalamount of the structural units (I), (II) and (III) to be copolymerized.An especially more preferred range is from 60 to 15 mol %. Moreover, itis preferred that the molar ratio [(I)/(II)] of the structural units (I)to the structural units (II) is from 75/25 to 95/5. A more preferredrange is from 78/22 to 93/7. Furthermore, it is preferred that theamount of the structural units (IV) to be copolymerized is substantiallyequimolar to the total amount of the structural units (II) and (III).

On the other hand, in the case where the copolymer does not contain thestructural units (II), it is preferred that the amount of the structuralunits (I) to be copolymerized is from 40 to 90 mol % based on the totalamount of the structural units (I) and (III) in view of flowability. Anespecially preferred range is from 60 to 88 mol %. It is preferred thatthe amount of the structural units (IV) to be copolymerized issubstantially equimolar to the amount of the structural units (III) tobe copolymerized.

In the above, being substantially equimolar means that the units of acomponent used in the main chain of a polymer excluding the ends areequimolar to the units of another component used in the main chain ofthe polymer excluding the ends, but that the units of a component usedin the ends is not always equimolar to the units of another componentused in the ends.

Furthermore, as the liquid crystal polyester amide, preferred is apolyester amide containing the p-iminophenoxy units produced fromp-aminophenol in addition to the above-mentioned structural units (I)through (IV) and capable of forming an anisotropic melt phase.

The liquid crystal polyester and liquid crystal polyester amide can haveany of the following compounds copolymerized as a component other thanthe components represented by said structural units (I) through (IV) tosuch an extent that the liquid crystallinity is not impaired: aromaticdicarboxylic acids such as 3,3′-diphenyldicarboxylic acid and2,2′-diphenyldicar-boxylic acid, aliphatic dicarboxylic acids such asadipic acid, azelaic acid, sebacic acid and dodecanedioic acid,alicyclic dicarboxylic acids such as hexahydroterephthalic acid,aromatic diols such as chlorohydroquinone, 3,4′-dihydroxybiphenyl,4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenyl sulfide,4,4′-dihydroxybenzophenone and 3,4′-dihydroxybiphenyl, aliphatic andalicyclic diols such as propylene glycol, 1,4-butanediol,1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol and1,4-cyclohexanedimethanol, aromatic hydroxycarboxylic acids such asm-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, p-aminobenzoicacid, etc.

The method for producing the liquid crystal resin (c) is not especiallylimited, and any publicly known polyester polycondensation method can beused for producing it.

Furthermore, the melt viscosity of the liquid crystal resin (c) is notespecially limited. However, to exhibit the effects more remarkably, itis preferred that the value measured at the melting point of the liquidcrystal resin +10° C. is 100 Pa·s or less. A more preferred range isfrom 0.1 to 50 Pa·s, and the most preferred range is from 0.5 to 30Pa·s. Meanwhile, the melt viscosity is the value measured using a Kokatype flow tester and a nozzle with a nozzle diameter of 0.5 mm and anozzle length of 10 mm at a shear rate of 1000 sec⁻¹.

In this case, the melting point is obtained as described below. In thedifferential calorimetry, the endothermic peak temperature (Tm1)observed when the polymer is heated from room temperature at a heatingrate of 20° C./min is identified, and the polymer is kept at atemperature of Tm1+20° C. for 5 minutes and once cooled to roomtemperature at a cooling rate of 20° C./min, then being heated at aheating rate of 20° C. again, to observe the endothermic peaktemperature (Tm2) to be identified as the melting point.

The amount of one or more resins (c) selected from PPSs and liquidcrystal resins, to be added to the composition consisting of thepolyester resin (a) and the olefin-based resin (b) is from 0.5 to 30parts by weight per 100 parts by weight as the total amount of (a) and(b), for further improving the chemicals resistance and imparting suchproperties as flowability during processing without impairing thetoughness and impact properties at low temperature. A preferred range isfrom 1 to 30 parts by weight, and a more preferred range is from 1 to 20parts by weight. A further more preferred range is from 2 to 20 parts byweight, and an especially preferred range is from 3 to 15 parts byweight. The most preferred range is from 5 to 15 parts by weight. If theamount of one or more resins (c) selected from PPSs and liquid crystalresins is too small, the effect of improving the chemicals resistance issmall. If the amount is too large, the properties at low temperaturetend to decline.

To the polyester resin composition, the antioxidant and other additivesas described below can also be added.

To keep high heat resistance and thermal stability, it is preferred tolet the polyester resin composition contain one or more antioxidantsselected from phenol-based and phosphorus-based compounds. It ispreferred that the amount of the antioxidant added is 0.01 part byweight or more, especially 0.02 part by weight or more per 100 parts byweight as total of the ingredients (a) and (b), in view of the effect ofimproving heat resistance. In view of the gas component generated duringmolding, it is preferred that the amount is 5 parts by weight or less,especially 1 part by weight or less. Furthermore, it is preferred to usea phenol-based antioxidant and a phosphorus-based antioxidant together,since the effects of keeping heat resis-tance, thermal stability andflowability are especially large.

As the phenol-based antioxidant, a hindered phenol-based compound can bepreferably used. Examples of it include triethylene glycolbis[3-t-butyl(5-methyl-4-hydroxyphenyl)propionate], N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide),tetrakis[meth-ylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane,pentaerythrityltetrakis[3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate],1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)-trione,1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,4,4′-butyliden-bis(3-methyl-6-t-butylphenol),n-octadecyl-3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate,3,9-bis[2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl]-2,4,8,10-tetra-oxaspiro[5,5]undecane,1,3,5-trimethyl-2,4,6-tris-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, etc.

Above all, an ester type high molecular hindered phenol-based compoundis preferred. Particularly,tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane,pentaerythrityltetrakis[3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate],3,9-bis[2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane,etc. can be preferably used.

Examples of the phosphorus-based antioxidant includebis(2,6-di-t-butyl-4-methyl-phenyl)pentaerythritol-di-phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol-di-phosphite,bis(2,4-di-cumylphenyl)pentaerythritol-di-phosphite,tris(2,4-di-t-butylphenyl)phosphite,tetrakis(2,4-di-t-butylphenyl)-4,4′-bisphenylene phosphite,di-stearylpentaerythritol-di-phosphite, triphenyl phosphite,3,5-di-butyl-4-hydroxybenzyl-phosphonate diethyl ester, etc.

Above all, to decrease the volatilization and decomposition of theantioxidant in the compound of the polyester resin, an antioxidant witha high melting point is preferred. Particularly,bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol-di-phosphite,bis(2,4-di-cumylphenyl)pentaerythritol-di-phosphite, etc. can bepreferably used.

Furthermore, to the polyester resin composition, a resin other than theolefin-based resin can be added to such an extent that desirable effectsare not impaired. For example, if a small amount of a highly crystallinethermoplastic resin is added, moldability can be improved. However, itis not preferred that the amount of the thermoplastic resin correspondsto more than 30 wt % of the entire composition, since the featurespeculiar to the polyester resin are impaired. Especially it is preferredthat the amount added corresponds to 20 wt % or less. Examples of thethermoplastic resin include a polyamide resin, modified poly-phenyleneether resin, polysulfone resin, polyallyl sulfone resin, polyketoneresin, poly-etherimide resin, polyarylate resin, polyethersulfone resin,polyetherketone resin, polythio-etherketone resin, polyetheretherketoneresin, polyimide resin, polyamideimide resin, poly-ethylenetetrafluoride resin, etc. Furthermore, for the purpose of modification,the following compounds can be added. It is possible to add a couplingagent such as an isocyanate-based compound, organic silane-basedcompound, organic titanate-based compound, organic borane-based compoundor epoxy compound, a plasticizer such as a polyalkylene oxideoligomer-based compound, thioether-based compound, ester-based compoundor organic phosphorus-based compound, a crystal nucleating agent such astalc, kaolin, organic phosphorus compound or polyetheretherketone, ametal soap such as montanic acid wax, lithium stearate or aluminumstearate, a releasing agent such as ethylenediamine/stearic acidisebacicacid polycondensation product or silicone-based compound, a colorprotection agent such as a hypophosphite, and other ordinary additivessuch as a lubricant, ultraviolet inhibitor, coloring agent, flameretarder and foaming agent. It is not preferred that the amount of anyof the above-mentioned compounds exceeds 20 wt % of the entirecomposition, since the properties peculiar to the polyester resin areimpaired. Preferred is 10 wt % or less, and more preferred is 1 wt % orless.

A filler can also be added to the polyester resin composition obtainedby the method to such an extent that the effects are not impaired.Examples of the filler include fibrous fillers such as glass fibers,carbon fibers, potassium titanate whiskers, zinc oxide whiskers, calciumcarbonate whiskers, wollastonite whiskers, aluminum borate whiskers,aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers,asbestos fibers, gypsum fibers and metal fibers, non-fibrous fillers,for example, silicates such as talc, wollas-tonite, zeolite, sericite,mica, kaolin, clay, pyrophyllite, bentonite, asbestos and aluminasilicate, metal compounds such as silicon oxide, magnesium oxide,alumina, zirconium oxide, titanium oxide and iron oxide, carbonates suchas calcium carbonate, magnesium carbonate and dolomite, sulfates such ascalcium sulfate and barium sulfate, hydroxides such as calciumhydroxide, magnesium hydroxide and aluminum hydroxide, glass beads,glass flakes, glass powder, ceramic beads, boron nitride, siliconcarbide, carbon black, silica, graphite, etc. They can also be hollow,and two or more of these fillers can also be used together. Furthermore,any of these fillers can also be pre-treated with a coupling agent suchas an isocyanate-based compound, organic silane-based compound, organictitanate-based compound, organic borane-based compound or epoxycompound, before it is used.

It is necessary that the polyester resin composition has a morphology inwhich the polyester resin 1 forms a continuous phase (matrix) while theolefin-based resin 2 forms a dispersion phase (sea-island structure) asshown in FIG. 1, and that the average particle size of the olefin-basedresin forming the dispersion phase is from 0.01 to 2 μm, preferably from0.01 to 1 μm, in order to achieve a high balance between flexibility andimpart properties at low temperature. In this regard, the morphology ofthe polyester resin composition of this invention is not limited to thatof FIG. 1. The form of the olefin-based resin particles can benon-circular, for example, polygonal or virtually ellipsoidal. If thedispersed particles of the olefin-based resin cohere to each other toform particles with an average particle size of more than 2 μm, thepolyester resin conmosition is unlikely to have good low-tempratureproperties and tends to decline in chemicals resistance. Furthermore, inthe case where the polyester does not form a continuous phase, thepolyester resin composition declines in flowablity and chemicalsresistance. In the case where the polyester resin composition has theabove-mentioned morphology, it is excellent in low-temperatureproperties and especially excellent in chemicals resistance andflowability.

The average particle size of the olefin-based resin in this case isobtained as described below. An ASTM Type 1 dumbbell specimen isobtained by molding the polyester resin composition, and is cut in thesectional area direction of the dumbbell specimen at its centralportion, to obtain a thin section of 0.1 μm or less. It is observed witha transmission electron microscope (magnification 10,000-fold), and themaximum diameters and the minimum diameters of given 100 dispersedparticles of the olefin-based resin are measured. The maximum diametersand the minimum diameters are averaged to obtain mean values which arefurther averaged to obtain a number average particle size.

Furthermore, in the polyester resin composition, it is preferred thatthe PPS resin or liquid crystal resin (c) is dispersed as particles withan average particle size of 1 to 100 nm in the polyester resin phase. Amore preferred range is from 1 to 80 nm, and the most preferred range isfrom 1 to 50 nm. If the polyester resin composition has this morphology,it has especially excellent chemicals resistance. If it has a structurein which the PPS resin or liquid crystal resin (c) is very finely anduniformly dispersed, the chemicals resistance of the polyester resin canbe dramatically improved. To form the fine and uniform dispersionstructure, it is preferred that the amount of the carboxyl end groups ofthe polyester resin (a) is in a range from 30 to 80 eq/t. Moreover, inthe case where the PPS resin is used as the ingredient (c), it ispreferred that the ash content, melt viscosity and chloroform extractioncontent of the PPS resin are in the above-mentioned specific ranges.

It is preferred that the weight reduction rate of the polyester resincomposition after it has been immersed in 23° C. hexafluoroisopropanol(hereinafter abbreviated as HFIP) for 1 hour is from 0 to 5%. It is notpreferred that the weight reduction rate is larger than 5%, since thepolyester resin composition cannot be used in any application requiringa contact with a chemical solution, since it is low in chemicalsresistance. Furthermore, it is preferred that the tensile breakelongation measured at a temperature of −40° C. according to ASTM-D638is from 20 to 400%, and that the notched impact strength measuredaccording to ASTM-D256 is from 500 to 2000 J/m. It is more preferredthat the tensile break elongation is from 30 to 400%, and that thenotched impact strength is from 600 to 2000 J/m. It is not preferredthat the respective properties do not conform to the above-mentionedranges, since the use in a cold area or in a low temperature environmentis limited.

It is preferred that the exothermic peak temperature (Tmc) of thepolyester resin composition observed during cooling from 300° C. at acooling rate of 20° C./min in differential calorimetry is from 190 to220° C. in the case where polyethylene terephthalate is used as thepolyester resin (a). A more preferred range is from 195 to 220° C. Inthis case, the moldability and fast molding cycles in injection moldingcan be improved.

As a typical method for producing the polyester resin composition, theraw materials can be fed into a melt kneading machine such as asingle-screw or twin-screw extruder, Banbury mixer, kneader or mixingroll mill, and are kneaded at a processing temperature higher than themelting point of the polyester resin. For controlling the morphology ofthis invention and the particle size of the olefin-based resin (b) asdescribed above, it is necessary to keep the shearing force relativelyhigh. Furthermore, it is necessary to keep the residence time duringkneading short. If these conditions are combined, the polyester resincan be made to form a continuous phase while the cohesion of theolefin-based resin is prevented. Particularly it is preferred that atwin-screw extruder is used, that the kneading temperature is themelting point of the polyester resin +5 to 20° C., and that theresidence time is from 1 to 5 minutes. In this case, the order of mixingraw materials is not especially limited. In one method, all the rawmaterials can be mixed and melt-kneaded by the above-mentioned method.In another method, some raw materials can be mixed and melt-kneaded bythe above-mentioned method, and further the remaining raw materials canbe mixed, the mixture being melt-kneaded. In a further other method,some raw materials can be mixed, and while they are melt-kneaded by asingle-screw or twin-screw extruder, the remaining raw materials can bemixed using a side feeder. Any one of these and other methods can beused. Moreover, for minor ingredients, the following method can also beemployed. After the other ingredients have been kneaded and pelletizedby the above-mentioned method or the like, they are added beforemolding, so that the entire mixture can be molded

The polyester resin composition is especially useful for an applicationas injection-molded parts, since it is excellent in impact propertiesand flowability. It is especially suitable for use as structuralmaterials such as pipes and cases for general apparatuses and motorvehicles, molded parts with metallic inserts for electric and electronicuse, etc.

Our resins are described below more particularly in reference toexamples since they have excellent flexibility and impact properties inlow temperature atmosphere and also has excellent flowability andchemicals resistance.

[Amount of Carboxyl End Groups]

A polyester resin was dissolved in m-cresol, and the potentiometrictitration of the m-cresol solution was carried out using an alkalisolution. The amount of carboxyl end groups was expressed as an amountper ton of the polymer.

[Observation of Morphology]

An injection molding machine (SG75H-MIV produced by Sumitomo HeavyIndustries, Ltd., cylinder temperature 280° C., mold temperature 130°C.) was used to injection-mold a polyester resin composition, forobtaining an ASTM Type 1 dumbbell specimen. From its central portion, athin section of 0.1 μm or less was obtained by cutting and observedusing a transmission electron microscope. The morphology was evaluatedaccording to the following criterion:

-   -   A: The polyester resin forms a continuous phase while the        olefin-based resin forms a dispersion phase, as shown in FIG. 1.    -   B: The polyester resin and the olefin-based resin form a        co-continuous phase as shown in FIG. 2.        [Average Particle Size]

For measuring the average particle size of an olefin-based resin, as inthe above-mentioned observation of morphology, a thin section of aspecimen obtained by injection molding was observed using a transmissionelectron microscope at a magnification of 10,000 times. The maximumdiameters and the minimum diameters were measured using image processingsoftware “Scion Image” and their mean values were obtained for 100dispersed particles of the olefin-based resin. Then, the 100 mean valueswere further number-averaged, and the obtained value was defined as theaverage particle size. Furthermore, the particle sizes of the dispersedparticles of the PPS or liquid crystal resin were obtained similarly,except that they were observed at a magnification of 100,000 times.

[Lower Limit Pressure of Molding]

An injection molding machine (SG75H-MIV produced by Sumitomo HeavyIndustries, Ltd., cylinder temperature 280° C., mold temperature 130°C.) was used to injection-mold a polyester resin composition, forpreparing a specimen. The lowest filling pressure in this case wasmeasured. However, in the case where polybutylene terephthalate resinwas used as the polyester resin, the cylinder temperature was set at260° C. and the mold temperature, 80° C.

[−40° C. impact strength]

A polyester resin composition was injection-molded as described above,to prepare a specimen for impact strength specified in ASTM-D256. Thenotched impact strength (⅛ inch thickness) was measured according toASTM-D256, except that the measuring temperature in the atmosphere was−40° C.

[−40° C. Tensile Break Elongation]

A polyester resin composition was injection-molded as described above,to obtain an ASTM Type 1 dumbbell specimen. The tensile break elongation(⅛ inch thickness) was measured according to ASTM-D638, except that thetemperature in the atmosphere was −40° C.

[Chemicals Resistance]

An ASTM Type 1 dumbbell specimen was immersed in toluene of 60° C. for24 hours, and after completion of immersion, the surface of the dumbbellspecimen was observed with an optical microscope to see whether or notthe surface was roughened partially (voids, etc.).

-   -   A: There were few surface roughened portions.    -   B: Surface roughened portions accounted for 30% or less.    -   C: Surface roughened portions accounted for about 50%.    -   D: Surface roughened portions accounted for 100%.    -   E: The olefin-based resin dissolved out.        [HFIP Resistance]

An ASTM Type 1 dumbbell specimen was immersed in hexafluoroisopropanol(HFIP) of 23° C. for 1 hour. It was weighed before and after immersion,to calculate the weight reduction rate.Weight reduction rate=[(Weight before immersion treatment)−(Weight afterimmersion treatment)÷Weight before immersion treatment]×100 [%][Hydrolysis Resistance]

An ASTM Type 1 dumbbell specimen was treated at a constant temperatureof 60° C. at a constant humidity of 95% RH for 3000 hours, and thetensile break elongation was measured according to ASTM-D638.

[Ash Content]

-   -   (1) Five to six grams of a PPS were weighed and placed on a        platinum dish burned at 583° C. and cooled.    -   (2) The PPS was preliminarily burned at 450 to 500° C. together        with the platinum dish.    -   (3) The preliminarily burned PPS sample was placed in a muffle        furnace set at 583° C. together with the platinum dish, to be        burned for about 6 hours till it was perfectly incinerated.    -   (4) It was cooled in a desiccator and weighed.    -   (5) The ash content was calculated from the formula: Ash content        (wt %)=(Weight of ash content (g)/Weight of sample (g))×100        [Chloroform Extraction Content]

Ten grams of a PPS polymer were weighed and placed in a thimble, andSoxhlet extraction was carried out (bath temperature 120° C., 5 hours)using 200 mL of chloroform. After completion of extraction, chloroformwas removed, and the remaining amount was weighed, the chloroformextraction content per polymer weight being calculated.

[Exothermic Peak Temperature (Tmc)]

DSC-7 produced by Perkin Elmer was used to hold about 8 mg of a samplepolymer at 300° C. for 5 minutes and scanned at a cooling rate of 20°C./min, to measure the exothermic peak temperature (Tmc).

[Molding Cycles]

An injection molding machine (SG75H-MIV produced by Sumitomo HeavyIndustries, Ltd., cylinder temperature 280° C., mold temperature 130°C., the mold allowed the production of two ASTM Type 1 dumbbellspecimens) was used to injection-mold a polyester resin composition, forfinding the maximum number of injection times per hour (shots/hr) duringwhich good ASTM Type 1 dumbbell specimens could be obtained. However, inthe case where polybutylene terephthalate resin was used as thepolyester resin, the cylinder temperature was set at 260° C., and themold temperature, 80° C.

REFERENCE EXAMPLE 1

Method for Producing Polyphenylene Sulfide Resin (C-1)

A 20-liter autoclave with a stirrer and having a valve at the bottom wascharged with 2383 g (20.0 moles) of 47% sodium hydrosulfide (produced bySankyo Kasei Co., Ltd.), 831 g (19.9 moles) of 96% sodium hydroxide,3960 g (40.0 moles) of N-methyl-2-pyrrolidone (hereinafter abbreviatedas NMP), and 3000 g of ion exchange water. While nitrogen was kept fedat atmospheric pressure, the reaction vessel was gradually heated up to225° C., taking about 3 hours, to distil away 4200 g of water and 80 gof NMP, and the reaction vessel was cooled to 160° C. The amount ofwater remaining in the system per mole of the supplied alkali metalsulfide was 0.17 mole. Furthermore, the amount of hydrogen sulfidescattered per mole of the supplied alkali metal sulfide was 0.021 mole.

Then, 2942 g (20.0 moles) of p-dichlorobenzene (produced bySigma-Aldrich) and 1515 g (15.3 moles) of NMP were added, and thereaction vessel was sealed under nitrogen gas. Subsequently withstirring at 400 rpm, the reaction vessel was heated from 200° C. to 227°C. at a rate of 0.8° C./min, heated up to 274° C. at a rate of 0.6°C./min, held at 274° C. for 50 minutes, and heated up to 282° C. Theejection valve at the bottom of the autoclave was opened, and underpressurization with nitrogen, the content was flashed into a vessel witha stirrer, taking 15 minutes. It was stirred for a while at 250° C. toremove most of NMP, and to recover a solid matter containingpolyphenylene sulfide (PPS) and salts.

The obtained solid matter and 15120 g of ion exchange water were fedinto an autoclave with a stirrer, and washed at 70° C. for 30 minutes,then being suction-filtered using a glass filter. Subsequently 17280 gof ion exchange water heated to 70° C. was poured into the glass filterand suction-filtered to obtain a cake.

The obtained cake, 11880 g of ion exchange water and 4 g of calciumacetate monohydrate (produced by Sigma-Aldrich) were fed into anautoclave with a stirrer, and the atmosphere in the autoclave wasreplaced by nitrogen. The autoclave was heated up to 192° C. and heldfor 30 minutes. Subsequently, the autoclave was cooled, and the contentwas taken out.

The content was suction-filtered using a glass filter, and 17280 g of70° C. ion exchange water was poured into the filter andsuction-filtered, to obtain a cake. The obtained cake was dried in hotair at 80° C. and further dried in vacuum at 120° C. for 24 hours, toobtain a dry PPS. The obtained PPS had an ash content of 0.6 wt %, amelt viscosity of 12 Pa·s (orifice 0.5 diameter×10 mm, 300° C., shearrate 1000 sec⁻¹), and a chloroform extraction content of 3.8%.

REFERENCE EXAMPLE 2

Method for Producing Polyphenylene Sulfide Resin (C-2)

A 20-liter autoclave with a stirrer was charged with 2383 g (20.0 moles)of 47% sodium hydrosulfide (produced by Sankyo Kasei Co., Ltd.), 848 g(20.4 moles) of 96% sodium hydroxide, 3267 g (33 moles) of NMP, 531 g(6.5 moles) of sodium acetate and 3000 g of ion exchange water. Whilenitrogen was kept fed at atmospheric pressure, the reaction vessel wasgradually heated up to 225° C., taking about 3 hours, to distil away4200 g of water and 80 g of NMP, and subsequently, the reaction vesselwas cooled to 160° C. The scattered amount of hydrogen sulfide was 0.018mole per mole of the supplied alkali metal sulfide.

Then, 3031 g (20.6 moles) of p-dichlorobenzene (produced bySigma-Aldrich) and 2594 g (26.2 moles) of NMP were added, and thereaction vessel was sealed under nitrogen gas. With stirring at 400 rpm,the reaction vessel was heated up to 227° C. at a rate of 0.8° C./min,subsequently heated up to 270° C. at a rate of 0.6° C./min, and held at270° C. for 140 minutes. Then, while the reaction vessel was cooled downto 250° C. at a rate of 1.3° C./min, 684 g (38 moles) of ion exchangewater was pressed in the autoclave. Then, the reaction vessel was cooleddown to 200° C. at a rate of 0.4° C./min, and subsequently quicklycooled to about room temperature.

The content was taken out and diluted with 10 liters of NMP, and themixture was separated into the solvent and a solid matter using a sieve(80 mesh). The obtained particles were washed with 20 liters of warmwater several times, and filtered. The residue was fed into 10 liters ofNMP heated to 100° C., and the mixture was stirred for about 1 hour andfiltered. The residue was further washed with hot water several times.Then, it was washed with 20 liters of warm water containing 9.8 g ofacetic acid, and filtered. The residue was washed with 20 liters of warmwater and filtered, to obtain PPS polymer particles. They were dried inhot air at 80° C., and dried in vacuum at 120° C. for 24 hours, toobtain a dry PPS. The obtained PPS had an ash content of 0.02 wt %, amelt viscosity of 40 Pa·s (orifice 0.5 diameter×10 mm, 300° C., shearrate 1000 sec⁻¹), and a chloroform extraction content of 0.4%.

REFERENCE EXAMPLE 3

Method for Producing Liquid Crystal Resin (C-3)

A reaction vessel with stirring blades and a distillate pipe was chargedwith 901 parts by weight of p-hydroxybenzoic acid, 126 parts by weightof 4,4′-dihydroxybiphenyl, 112 parts by weight of terephthalic acid, 346parts by weight of polyethylene terephthalate with an intrinsicviscosity of about 0.6 dl/g and 884 parts by weight of acetic anhydride.The reaction vessel was heated up to 150° C., taking 2 hours, heatedfrom 150° C. to 250° C., taking 3 hours, heated from 250° C. to 300° C.,taking 2 hours, made to react at 300° C. for 1.5 hours, reduced inpressure to 0.5 mm Hg at 300° C., taking 1.5 hours, and further made toreact for 10 minutes for polymerization. As a result, a liquid crystalresin (C-3) composed of 72.5 molar equivalents of aromatic oxycarbonylunits, 7.5 molar equivalents of aromatic dioxy units, 20 molarequivalents of ethylene dioxy units, and 27.5 molar equivalents ofaromatic dicarboxylic acid units and having a melting point of 265° C.and a melt viscosity of 13 Pa·s (orifice 0.5 diameter×10 mm, shear rate1000 sec⁻¹) at 275° C. was obtained.

REFERENCE EXAMPLE 4

Method for Producing Liquid Crystal Resin (C-4)

A reaction vessel with stirring blades and a distillate pipe was chargedwith 907 parts by weight of p-hydroxybenzoic acid, 457 parts by weightof 6-hydroxy-2-naphthoic acid and 873 parts by weight of aceticanhydride, and polymerization was carried out under the same conditionsas those used for producing C-1. As a result, a liquid crystal resin(C-4) composed of 73 molar equivalents of oxybenzoate units and 27 molarequivalents of 6-oxy-2-naphthalate units and having a melting point of283° C. and a melt viscosity of 42 Pa·s (orifice 0.5 diameter×10 mm,shear rate 1000 sec⁻¹) at 293° C. could be obtained.

EXAMPLES 1 TO 13 AND COMPARATIVE EXAMPLES 1 TO 6

The PPS C-1 and PPS C-2 respectively described in the above referenceexamples and the following ingredients were dry-blended at the ratiosshown in Table 1. Then, Model TEX30 twin-screw extruder produced by TheJapan Steel Works, Ltd. was used to melt-knead the blends with thecylinder temperature set at 250 to 280° C. at a screw speed of 200 rpm,to make strands which were then pelletized using a strand cutter. Thepellets were dried by dehumidification at 120° C. overnight and aninjection molding machine (SG75H-MIV produced by Sumitomo HeavyIndustries, Ltd., cylinder temperature 280° C. and mold temperature 130°C., or cylinder temperature 260° C. and mold temperature 80° C. whenpolybutylene terephthalate resin was used as the polyester resin) wasused to injection-mold the polyester resin compositions, for producingspecimens. Furthermore, as shown in Table 1, the following antioxidantswere added as required during melt kneading. The low-temperatureproperties, morphology, etc. of each sample were measured, and theresults were as shown in Table 1. The compositions of examples weresuperior in low-temperature properties (flexibility, impact properties,etc.), flowability, moldability, chemicals resistance, etc., but thoseof comparative examples were inferior in low-temperature properties,flowability, moldability and chemicals resistance.

The following polyester resins (a) were used in the examples andcomparative examples.

-   -   (A-1): Polyethylene terephthalate resin of 0.59 in intrinsic        viscosity and 49 eq/t in the amount of carboxyl end groups    -   (A-2): Polyethylene terephthalate resin of 0.66 in intrinsic        viscosity and 38 eq/t in the amount of carboxyl end groups    -   (A-3): Polyethylene terephthalate resin of 0.75 in intrinsic        viscosity and 13 eq/t in the amount of carboxyl end groups    -   (A-4): Polybutylene terephthalate resin of 0.70 in intrinsic        viscosity and 35 eq/t in the amount of carboxyl end groups    -   (A-5): Polyethylene-2,6-naphthalene dicarboxylate resin of 0.65        in intrinsic viscosity and 45 eq/t in the amount of carboxyl end        groups    -   (A-6): Polyethylene terephthalate/2,6-naphthalene        dicarboxylate=92/8 (mol %) resin of 0.75 in intrinsic viscosity,        35 eq/t in the amount of carboxyl end groups, and 234° C. in        melting point

Similarly the following functional group-containing olefin copolymers(b-1) were used.

-   -   (B-1): Ethylene/glycidyl methacrylate=88/12 (wt %) with an MFR        of 3 g/10 mm (190° C., 2.16 kg load)    -   (B-2): Ethylene/glycidyl methacrylate=94/6 (wt %) copolymer with        an MFR of 3 g/10 min (190° C., 2.16 kg load)    -   (B-3): Maleic anhydride-modified ethylene/propylene=85/15 mol %        copolymer

Similarly the following ethylene/o:-olefin copolymers (b-2) were used.

-   -   (B-4): Ethylene/1-butene copolymer with an MFR of 3.5 g/10 min        (190° C., 2.16 kg load) and a density of 0.864/cm³    -   (B-5): Ethylene/1-butene copolymer with an MFR of 0.5 g/10 min        (190° C., 2.16 kg load) and a density of 0.861 g/cm³    -   (B-6): Ethylene/propylene=85/15 mol % copolymer with an MFR of        0.4 g/10 min (190° C., 2.16 kg load)

Antioxidants: The following two compounds were used.

-   -   Phenol-based antioxidant:        3,9-bis[2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyl-oxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane        Phosphorus-based antioxidant:        Bis(2,4-di-cumylphenyl)pentaerythritol-di-phosphite

TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 Polyester resins A-1 wt % 70 — — —— — — 80 60 70 A-2 wt % — 70 70 — — — 90 — — — A-4 wt % — — — 70 — — — —— — A-5 wt % — — — — 70 — — — — — A-6 wt % — — — — — 70 — — — — A-3 wt %— — — — — — — — — — Olefin- b-1 B-1 wt % 10 — 15 — — 10  3  5 — — basedB-2 wt % — 10 — 10 10 — — — 15 — resins B-3 wt % — — — — — — — — — 20b-2 B-4 wt % 20 — — 20 — 20 — — 25 10 B-5 wt % — 20 15 — 20 —  7 — — —B-6 wt % — — — — — — — 15 — — PPSs C-1 parts by 10  5 10 10  5 10  5  515 10 weight C-2 parts by — — — — — — — — — — weight AntioxidantsPhenol-based parts by — —   0.2   0.2   0.2   0.2   0.2   0.4   0.2  0.2 weight Phosphorus-based parts by — —   0.2   0.2   0.2   0.2   0.2  0.4   0.2   0.2 weight Observed morphology A A A A A A A A A A Averageparticle size Polyolefin μm   0.5   0.6   0.5   0.8   0.8   0.9   0.5  0.7   1.2   1.8 PPS nm 25 18 30 28 20 34 19 20 28 24 Tensile break−40° C. % 32 40 48 30 25 40 21 34 40 20 elongation Impact strength −40°C. J/m 640  750  750  610  520  650  520  680  850  500  HFIP resistanceWeight %   2.2   3.7   2.3   2.1   1.6   2.1   4.6   3.7   0.8   2.8reduction rate Hydrolysis Tensile break % 70 60 80 60 75 75 35 40 55 30resistance elongation Exothermic peak Tm c ° C. 199  194  200  — — —191  192  201  196  temperature Flowability Lower limit MPa · G   1.8  3.1   3.3   2.8   3.4   2.9   1.2   1.5   2.9   2.4 pressure ofmolding Molding cycles shots/hr 180  160  180  220  120  120  140  140 200  160  Chemicals resistance A A A A A A A A A A Examples ComparativeExamples 11 12 13 1 2 3 4 5 6 Polyester resins A-1 wt % 70 70 70 70 — —— — — A-2 wt % — — — — 70 — — — 55 A-4 wt % — — — — — — — — — A-5 wt % —— — — — — — — — A-6 wt % — — — — — — — — — A-3 wt % — — — — — 70 70 80 —Olefin- b-1 B-1 wt % 10 10 10 30 — 10 10 — 20 based B-2 wt % — — — — — ——  5 — resins B-3 wt % — — — — — — — — — b-2 B-4 wt % 20 20 20 — 30 2020 — — B-5 wt % — — — — — — — 15 25 B-6 wt % — — — — — — — — — PPSs C-1parts by — — — 10 — — 10 — 15 weight C-2 parts by  5 10 15 — 10 — —  5 —weight Antioxidants Phenol-based parts by   0.2   0.2   0.2 — —   0.2  0.2   0.2   0.2 weight Phosphorus-based parts by   0.2   0.2   0.2 — —  0.2   0.2   0.2   0.2 weight Observed morphology A A A A A A A A BAverage particle size Polyolefin μm   0.5   0.6   0.6   1.2   10   3.3  3.7   4.2 — PPS nm 42 49 53 190  45 — 220  230  310  Tensile break−40° C. % 38 32 30 10  7 35 30 24 17 elongation Impact strength −40° C.J/m 670  620  520  70 50 280  220  200  730  HFIP resistance Weight %  3.3   2.4   1.1   7.3 10 12   7.7   8.2   5.3 reduction rateHydrolysis Tensile break % 75 60 65 40  5 60 60 50 25 resistanceelongation Exothermic peak Tm c ° C. 186  190  194  181  178  172  180 175  188  temperature Flowability Lower limit MPa · G   2.8   2.5   2.2  5.3   3.0   6.0   5.3   3.8   6.1 pressure of molding Molding cyclesshots/hr 120  140  140  80 60 60 80 60 100  Chemicals resistance A A A CD D D B D

EXAMPLES 14 TO 25 and COMPARATIVE EXAMPLES 7 TO 11

The liquid crystal resins C-3 and C-4 respectively described in theabove reference examples and the respective ingredients used in Examples1 to 13 were dry-blended at the ratios shown in Table 2. Then, ModelTEX30 twin-screw extruder produced by The Japan Steel Works, Ltd. wasused to melt-knead the blends with the cylinder temperature set at 280to 300° C. at a screw speed of 200 rpm, to make strands which were thenpelletized using a strand cutter. The pellets were dried bydehumidification at 120° C. overnight and an injection molding machine(SG75H-MIV produced by Sumitomo Heavy Industries, Ltd., cylindertemperature 280° C. and mold temperature 130° C., or mold temperature80° C. when polybutylene terephthalate resin was used) was used toinjection-mold the polyester resin compositions, for producingspecimens. The low-temperature properties, morphology, etc. of eachsample were measured, and the results were as shown in Table 2. Thecompositions of examples were superior in low-temperature properties(flexibility, impact properties, etc.), flowability, moldability,chemicals resistance, etc., but those of comparative examples wereinferior in low-temperature properties, flowability, moldability andchemicals resistance.

TABLE 2 Examples 14 15 16 17 18 19 20 21 22 Polyester A-1 wt % 70 — — —— — — 80 60 resins A-2 wt % — 70 70 — — — 90 — — A-4 wt % — — — 70 — — —— — A-5 wt % — — — — 70 — — — — A-6 wt % — — — — — 70 — — — A-3 wt % — —— — — — — — — Olefin- b-1 B-1 wt % 10 — 15 — — 10  3  5 — based B-2 wt %— 10 — 10 10 — — — 15 resins B-3 wt % — — — — — — — — — b-2 B-4 wt % 20— — 20 — 20 — — 25 B-5 wt % — 20 15 — 20 —  7 — — B-6 wt % — — — — — — —15 — Liquid C-3 parts by 10  5 10 10  5 10  5  5 15 crystal weight resinC-4 parts by — — — — — — — — — weight Antioxidants Phenol-based parts by— —   0.2   0.2   0.2   0.2   0.2   0.4   0.2 weight Phosphorus- partsby — —   0.2   0.2   0.2   0.2   0.2   0.4   0.2 based weight Observedmorphology A A A A A A A A A Average Polyolefin μm   0.6   0.8   0.7  0.9   0.7   0.9   0.5   0.7   1.0 particle Liquid crystal nm 62 55 7065 45 59 50 51 75 size resin Tensile −40° C. % 30 45 50 31 35 40 25 3945 Impact −40° C. J/m 600  780  730  600  550  650  570  640  800  HFIPWeight %   1.8   3.5   2.3   2.4   1.7   2.0   4.2   3.8   1.3resistance reduction rate Hydrolysis Tensile break % 75 60 85 65 70 7530 45 60 resistance elongation Flowability Lower limit MPa · G   1.7  2.7   3.1   2.5   3.1   2.8   1.4   1.7   3.1 pressure of moldingMolding cycles shots/hr 160  140  160  180  110  120  120  130  160 Chemicals resistance A A A A A A A A A Examples Comparative Examples 2324 25 7 8 9 10 11 Polyester A-1 wt % 70 70 70 70 — — — — resins A-2 wt %— — — — 70 — — 55 A-4 wt % — — — — — — — — A-5 wt % — — — — — — — — A-6wt % — — — — — — — — A-3 wt % — — — — — 70 80 — Olefin- b-1 B-1 wt % —10 10 30 — 10 — 20 based B-2 wt % — — — — — —  5 — resins B-3 wt % 20 —— — — — — — b-2 B-4 wt % 10 20 20 — 30 20 — — B-5 wt % — — — — — — 15 25B-6 wt % — — — — — — — — Liquid C-3 parts by  5 — — 10 10 10  5 15crystal weight resin C-4 parts by —  5 10 — — — — — weight AntioxidantsPhenol-based parts by   0.2   0.2   0.2 — —   0.2   0.2   0.2 weightPhosphorus- parts by   0.2   0.2   0.2 — —   0.2   0.2   0.2 basedweight Observed morphology A A A A A A A B Average Polyolefin μm   1.8  0.7   0.9   1.3   10.1   3.5   4.2 — particle Liquid crystal nm 47 5268 210  77 190  160  380  size resin Tensile −40° C. % 25 35 35  9  7 2518 15 Impact −40° C. J/m 650  600  520  50 30 180  135  690  HFIP Weight%   3.3   3.4   1.7   6.9   9.5   7.5   9.2   5.9 resistance reductionrate Hydrolysis Tensile break % 50 75 80 50 10 50 55 30 resistanceelongation Flowability Lower limit MPa · G   3.4   2.6   2.3   6.5   2.4  3.7   2.4   5.5 pressure of molding Molding cycles shots/hr 140  110 140  65 60 70 40 80 Chemicals resistance A A A C D D B D

INDUSTRIAL APPLICABILITY

Provide a polyester resin composition having excellent mechanicalproperties, especially excellent flexibility and impact properties in alow temperature atmosphere as low as −40° C., and also having excellentflowability and chemicals resistance, and suitable for injectionmolding.

The polyester resin composition is especially useful for an applicationas injection-molded parts, since it is excellent in impact propertiesand flowability. It is especially suitable for use as structuralmaterials such as pipes and cases for general apparatuses and motorvehicles, molded parts with metallic inserts for electric and electronicuse, etc., since it has excellent flexibility and impact properties in alow temperature atmosphere and also having excellent flowability andchemicals resistance.

1. A polyester resin composition comprising: 1) 100 parts by weight of aresin composition consisting of 60 to 90 wt % of (a) a polyester resinwith an amount of carboxyl end groups of from 35 to 49 eq/t and is atleast one selected from the group consisting of polyethyleneterephthalate, polyethylene-2,6-naphthalene dicarboxylate and theircopolymers, and 10 to 40 wt % of (b) an olefin-based resin, and 2) 5 to15 parts by weight of (c) one or more resins selected from polyphenylenesulfide resins and liquid crystal resins, wherein said olefin-basedresin (b) comprises 3 to 20 wt % of (b-1) a functional group-containingolefin copolymer having at least one kind of functional groups selectedfrom carboxylic acid groups, carboxylic anhydride groups and epoxygroups and 7 to 25 wt % of (b-2) an ethylene/α-olefin copolymer obtainedby copolymerizing ethylene and an α-olefin with 3 to 20 carbon atoms;and the polyester resin (a) forms a continuous phase, while theolefin-based resin (b) is dispersed as particles with an averageparticle size of 0.01 to 2 μm in the composition, and the polyphenylenesulfide resin (c) or liquid crystal resin is dispersed in the polyesterresin (a) phase as particles having an average particle size of 1 to 100nm and the polyphenylene sulfide has a melt viscosity of 12 to 40 Pa·s.2. The polyester resin composition according to claim 1, the weightreduction rate of which after having been immersed in 23° C.hexafluoroisopropanol for 1 hour is from 0 to 5%.
 3. The polyester resincomposition according to claim 1, wherein the functionalgroup-containing olefin copolymer (b-1) is an olefin copolymer havingepoxy groups.
 4. The polyester resin composition according to claim 1,wherein the functional group-containing olefin copolymer (b-1) is acopolymer obtained from ethylene and/or an α-olefin and anαβ-unsaturated carboxylic acid glycidyl ester.
 5. The polyester resincomposition according to claim 1, wherein the ingredient (c) is apolyphenylene sulfide resin which has an ash content of 0.1 to 2 wt %.6. The polyester resin composition according to claim 1, wherein theingredient (c) is a polyphenylene sulfide resin which has a chloroformextraction content of 1 to 5 wt %.
 7. The polyester resin compositionaccording to claim 1, which has a tensile break elongation of 20 to 400%as measured according to ASTM-D638 at a temperature of −40° C. and animpact strength of 500 to 2000 J/m as measured according to ASTM-D-256.8. The polyester resin composition according to claim 1, wherein thepolyester resin (a) is polyethylene terephthalate, and the exothermicpeak temperature (Tmc) observed in the differential calorimetry of theresin composition during cooling from 300° C. at a cooling rate of 20°C./min is 190° C. or higher.